Buruli ulcer, an infectious disease caused by
Mycobacterium ulcerans, is the third most prevalent mycobacteriosis,
after tuberculosis and leprosy. This atypical mycobacteriosis has been reported
in over 30 countries, mainly those with tropical and subtropical climates, but
its epidemiology remains unclear. The first autochthonous cases of infection
in Brazil have recently been described, making this diagnosis important for
Brazilian dermatologists. Clinical manifestations vary from nodules, areas of
edema, and plaques, but the most typical presentation is a large ulcer, usually
in the limbs. Despite considerable knowledge about its clinical manifestations
in some endemic countries, in other areas the diagnosis may be overlooked. Therefore,
physicians should be educated about Buruli ulcer, since early diagnosis and
treatment, including measures to prevent disability, are essential for a good
outcome.

Buruli ulcer (BU), an infectious disease caused
by Mycobacterium ulcerans,1 is one of the most neglected tropical
diseases. It is the third mycobacteriosis in prevalence, after leprosy and tuberculosis.
M. Ulcerans is capable of producing mycolactone, an immunomodulatory macrolide
toxin that causes tissue necrosis2,3 and destroys the skin and soft tissues
with the formation of large ulcers, often in the arms or legs. In general, the clinical
presentation of ulcer is associated with a delay to seek medical treatment4
and with lack of adequate treatment. Patients not treated early often suffer from
functional disabilities in the long run, with joint movement impairment, which restricts
their ability to execute and participate in daily activities.5,6

Early diagnosis and a specific treatment for BU
associated with interventions that prevent disabilities are crucial for satisfactory
treatment results.7,8 When necessary, surgery associated with antimicrobial
therapy is the recommended treatment.7 When extensive lesions and complications
exist, the patient may need long periods of hospitalization, with severe socioeconomic
and psychosocial implications.9,10

Buruli ulcer has been reported in more than 30 countries,
especially in those with tropical and subtropical climate, but it can also occur
in a few countries where the disease has not yet been recognized. The number of reports
of affected patients grew considerably over the last few years.7 Despite
the several cases described, the epidemiology of BU remains unclear, even in endemic
countries.8 Limited knowledge of the disease, its focal distribution,
and the fact that it affects mainly poor rural communities contribute to the low
notification of cases.2

HISTORY

In 1897, Sir Albert Cook, a British physician who
worked at the Mengo Hospital in Kampala, Uganda, described skin ulcers that were
clinically consistent with Buruli ulcer (BU),7 but the first detailed
description of the disease caused by Mycobacterium ulcerans is attributed
to MacCallum et al. in Australia in 1948.11 In 1950, in the Belgium Congo
(current Democratic Republic of Congo), the first African case was reported and,
in that same year, Fenner identified the bacillus and named it Mycobacterium ulcerans.
1 Since 1959, several authors have described many patients with this disease
in tropical and subtropical regions of Central and West Africa.7,12 In
the Americas, it is a rare disease and very few cases have been reported. This mycobacteriosis
received several names according to the place where it occurred or was observed.
For instance, it was called Bairnsdale ulcer in Australia, Buruli ulcer in Uganda,
and Tora and Mexican ulcer in Mexico.12 The first Brazilian case was reported
by do Santos et al. only in 2007.13

In 1998, after an international conference organized
by the World Health Organization about the control of and research in Buruli Ulcer,
held in Yamoussoukro, Côte d'Ivoire (Ivory Coast), the Global Buruli Ulcer Initiative
was implemented. The initiative remains active until today, including several research
projects in different African countries, where Buruli ulcer is an endemic disease.

EPIDEMIOLOGY

Buruli ulcer frequently affects individuals who
live close to water bodies  slow flowing rivers, ponds, swamps, and lakes; however,
cases of the disease have been reported after flooding. Activities that are developed
close to the water, such as farming, constitute risk factors. Protective clothing
appears to reduce the risk of contracting the disease.7,8 In Benin, an
inverse relationship between the prevalence of the disease and how far the patient
lived from a river was found. The prevalence gradually increased from 0.6 to 32.6/1000
when the distance to a river shortened by 10 km.14

All ages and genders are affected, but most patients
are children younger than 15 years,14,15,16 with peak age of onset between
10 and 14 years. In adults, it is between 75 and 79 years.14 The high
rate of detection in elderly patients may be associated with the reactivation of
a latent disease.17 A study showed that even though there are no gender
differences among children and adults, men older than 59 years had a higher chance
of developing BU than women.17 This difference may be related to professional
activities and differences in access to health services.14

Buruli ulcer has been reported in 30 countries
from Africa, the Americas, Asia and Western Pacific, especially in tropical
and subtropical regions (Figure
1). The disease is a public health problem in Uganda, Nigeria, Gabon, Ghana,
Cameroon, Liberia, Côted'Ivoire, Malasia, Papua New Guinea, Togo, French
Guiana, and Republic of Benin.7,12 In Côte-d'Ivoire, approximately
15,000 cases have been registered since 1978. In Benin, nearly 15% of the population
is affected. In 1999, 6,000 new cases were reported in Ghana.18 A
few cases reported in North America and Europe were associated with international
travelers.19 Some cases have been reported in China, but the extension
of the disease is unknown. In the Americas, the disease appears to be more common
in the French Guiana (although fewer than 200 cases have been reported in 35
years) than in Suriname, Mexico or Peru, where very few cases have been confirmed
 fewer than 10 cases per country over the last 50 years. These numbers
may be only an indication of the presence of the disease, but do not reveal
the extent of the problem.8

The first Brazilian case was reported in 2007. A
65-year-old patient was seen at a health center in Brasilia showing two years of
clinical evolution of BU associated with osteomyelitis. The patient lived in a rural
area close to a water body, where the climate is hot and humid. Initially, leishmaniasis,
a common disease where the patient lives, was wrongly diagnosed. After a positive
culture for M. ulcerans from skin and bone tissue samples, the diagnosis of
BU was confirmed. 13 Despite being the first Brazilian case of BU, similarities
between the climate, vegetation, and habits in Brazil and endemic countries suggest
that Brazil may be a focus of the disease. Health professionals' lack of knowledge
about the disease makes the identification and epidemiological monitoring of BU difficult
in Brazil.

The second case, probably originary from the Brazilian
territory, was published by McGann et al. in November of 2009. It refers to an English
tourist who contracted the disease after a visit to the Brazilian Pantanal region,20
which shows that the disease may be more of a reality than imagined. Cases from nonendemic
countries are very rare. In the literature, only 21 such cases have been reported
so far, 8,21,22 including the last Brazilian case. One explanation for
them could be immigration from an endemic country for BU to non-endemic areas. The
disease could be contracted in the country of origin or by a traveler from a non-endemic
country. Infection by Mycobacterium ulcerans is among the main ulcers diagnosed
in travelers to West Africa, Central America and other Western countries, together
with leishmaniasis, diphtheria, and profound mycoses.19,21 Despite advanced
knowledge about the clinical symptoms of BU in endemic countries, in other areas
this diagnosis may be overlooked. Therefore, physicians should be aware of its symptoms,
since early diagnosis and proper treatment help prevent functional disabilities resulting
from the infection. BU is probably endemic in a broader area than often considered.

The exact prevalence of the disease is unclear due
to lack of knowledge about the disease among health professionals and the population
in general. This leads to significant undernotification. People who are mostly affected
by the disease live in remote rural areas, with little access to the health system.
There is great variation in the clinical presentation of the disease, which makes
confusion of BU with other diseases and tropical ulcers common. In addition, there
is no compulsory notification in many countries.

Based on various studies, it is now clear that
there is a relationship between BU and water, but the precise form of transmission
of M. ulcerans has not been established. An environmental factor not
yet identified associated with slow flowing water, to which populations that
live close to a water body are exposed, is thought to exist. There are reports
of a likely transmission by mosquito or insect bites.22-26 A research
study suggests that in Africa some water insects of the order Hemiptera (Naucoridae
and Belostomatidae) may harbor M. Ulcerans in their salivary glands and
transmist the disease to animals (Figure 2). A study showed
that infected Naucoris mosquitoes transmit the pathogen to rats through biting,
in addition to being naturally colonized by M. Ulcerans in endemic areas.23,24,25
These insects can fly many kilometers from their starting point and this may
explain why patients who do not live close to a water body can get infected,
but not as often as those who live closer to ponds and swamps.

More recent data from Australia suggest that salt
marsh mosquitoes test positive for M. Ulcerans DNA, although transmission
by this type of insect has not been recognized. Further research is in progress to
establish the exact role of insects and other factors in the transmission of the
disease to humans. If this is confirmed, BU will be the only disease caused by mycobateria
that is transmitted by insects.7,24,25,26

Inoculation also appears to occur through trauma.
27 In this case, skin contamination would occur as a result of direct
exposure to still water, gases from lagoons and surface of ponds or contaminated
objects. M. Ulcerans can enter the human body through several types of trauma,
from mild ones such as a hypodermal injection, to severe, like landmine injuries,
snake or even human bite. Two cases of human bite have been reported and this exemplifies
patient-to-patient transmission.28,29

A change in the epidemiology of BU has been attributed
to flooding, population growth, mining, extraction of wood from tropical forests,
and river damming, but there is no evidence of this causal association. Hypotheses
consider that M. ulcerans is introduced into new regions by insects, human
beings or other animals. Alternatively, the organism can be widely distributed in
the environment, in low numbers, but they significantly increase after certain events,
such as deforestation and flooding.16 Recent research studies suggest
that the prevalence of BU in Uganda appears to have reduced significantly. In this
country, the damming of Lake Vitoria dried the swamps at the margin of the Nile,
and this may have contributed to the dramatic reduction of the incidence of the disease.
14

IMMUNOLOGY AND ETIOPATHOGENY

M. ulcerans is an acid-alcohol resistant
bacillus (BARR) predominantly extracellular. Current data suggest that this mycobacterium
does not exist freely in the environment, as previously thought. It probably occupies
a specific niche within acquatic environments (for instance, small acquatic animals),
from where it is transmitted to humans by an unknown mechanism.7 Although
slow growing, M. ulcerans can be cultured on media used for mycobacteria (such
as Lowenstein-Jensen medium) provided the incubation temperature is kept between
29-33 ° C (lower than that for M. Tuberculosis), microaerophilic environment,
and pH between 5.4 and 7.4. There is a wide variability of data about the success
of isolation from clinical samples. Reference laboratories have reported high rates
of success in clinically confirmed cases using improved transportation and decontamination
methods.8

There is some variation among strains of M.
ulcerans from different geographical areas of Africa, the Americas, Asia,
and Australia (Figure 3), but the relationship between these
various strains and virulence in humans has not been established.8
The development of polymerase chain reaction (PCR) to promptly identify M.
ulcerans in clinical and environmental samples has improved the diagnosis
and comprehension about the epidemiology of BU. The PCR technique identified
repeated DNA sequences in the genome of M. ulcerans, IS2404.8,30
A direct relationship between the virulence of M. ulcerans and the number
of repeated IS2404 sequences appears to exist.31

Mycolactone is a heat-stable exotoxin, lypophilic,
that belongs to the group of macrolides and causes extensive, chronic, and necrotizing
damage to the papillary dermis, subcutaneous fat, and muscles (fasciae and bones
are sometimes affected), resulting in derformity and disability. The molecule is
active in extremely low concentrations and is not present in laboratory cultures.
16

Mycolactone molecules, when injected in laboratory
animals, are capable of producing massive necrosis similar to what is observed when
these animals are inoculated with M. ulcerans. With the full genome sequencing
of M. ulcerans, it became evident that the genetic information for mycolactone
synthesis is synthesized from a 174 kb plasmid known as pMUM001. This makes M.
ulcerans the only mycobacterium whose virulence is mediated by a plasmid. Mycobacterium
marinum and M. ulcerans are phylogenetically close, sharing from 98 to
99.8% of their genetic material.32 The molecular finding that most clearly
separates these two species is the production of mycolactone by M. ulcerans.
8,16,31,33 Another mycobacterium, M. Lifandii, isolated from frogs
in West Africa, is a pathogen associated with M. ulcerans and M. Marinuns.
M. Liflandii also presents the IS2404 sequence and all the genes that codify
mycolactone, except the one that codifies monooxygenase p450.2 M. Liflandii
can produce ulcers similar to BU in frogs.8

M. ulcerans strains isolated in particular
regions show remarkable similarity, but important differences in the production of
mycolactone according to geographical areas have been identified. This may reflect
regional differences in the clinical presentation and virulence of M. ulcerans.
This macrolide has been shown to be the main virulence factor and presents cytotoxic,
analgesic, and immunosupressive activity in the infection caused by M. ulcerans.
33

The various strains of M. ulcerans produce
a macrolide family with identical biological activity, but with different potency.
34 The first type of macrolide identified was mycolactone A/B, followed
by a family of variants of this toxin (mycolactones C, D, and E). Studies compared
strains of M. ulcerans from different continents and verified that mycolactone
A/B was the most powerful macrolide.35 African strains and one from Malasia
produced more mycolactone variants (at least four variants in addition to types A/B).
This could contribute to greater cytopathogenicity of this particular strain.36
Therefore, a region with more extensive and disseminated BU cases is found with higher
frequency in Africa, where mycolactones A/B are more abundant. This is different
from Australia, where mycolactone C appears more often than mycolactones A and B.

In vitro studies have shown that the immunosupressive
activity of mycolactone occurs through the inhibition of the production of Th1-interleukin
(IL) 12 cytokines, interferon (IFN)-alpha, and suppression of the production of tumoral
necrosis factor (TNF) by monocytes. These cytokines are important in the control
of mycobateria infection.37 Studies on tuberculosis and leprosy have shown
that Th2 cytokines (IL-4, IL-13) and antiinflammatory cytokines, such as IL-10 and
tumoral growth factor (TGF), have a negative effect on the control of mycobacteria
proliferation.38,39 Kiszewski et al. showed that in ulcers with granulomas
there is a significantly higher expression of IFN¿ and lower bacillary load. However,
the cytokine profile found in BU without granulomas was similar to the one found
in active progressive tuberculosis, in which there is reduction of Th1 cell funtion
and increase of Th2 activity, associated with a high production of IL 10 and TGFÃ.
34,38 This could indicate that the presence of granuloma signals better
immunological protection.34 Hence, it appears that there is a mixed model
of proand antiinflammatory cytokines in areas of ulcerative lesions of BU, which
vary based on the evolution of the disease. Recent ulcerated lesions have a predominant
immunosuppressive cytokine profile, with high bacillary load, whereas old ulcers
have a combination of cytokines with predominance of IFN¿ and low bacillary load
and typical granuloma. In addition, disseminated disease and osteomyelitis have been
associated with defects in the formation of granulomas.40,41

Many healthy individuals in endemic areas for Buruli
ulcer show a specific humoral immune response to M. ulcerans, suggesting that
the disease thrives only in a limited group of individuals who have been infected
by M. ulcerans. The immune response mediated by Th1 lymphocytes is protective
against BU; however, Th2, which is targeted to the production of antibodies, does
not control the disease. Humoral immune response with production of IgM antibodies
appears to be more frequent in patients with active ulcers than in their relatives.
Co-infection by HIV has not been reported as a risk factor, but more severe clinical
forms of BU have been described in seropositive patients.42 A few individuals
could escape the disease due to an individual protection centered in a cellular immune
response.

HISTOPATHOLOGY

It is possible to divide BU into four histopathological
stages of evolution:43

Non-ulcerated necrotic stage: the epidermis is intact, but it is
often hyperplastic. The upper dermis is usually preserved, but it can show
various degrees of collagen degeneration, edema, and discreet infiltration
of inflammatory cells. Vasculitis, with occlusion of vessels by thrombus,
can also be observed. In this stage and in the initial ulcerative phases,
coagulation necrosis in the lower portion of the dermis, subcutaneous tissue,
and fascia is easily identified. In these areas, predominantly extracellular
BAAR form clusters that are easily detected in the center of the lesion in
the deep layers of the dermis and in the adipose paniculus. Calcification
can also be detected. Another finding is the presence of denucleated adipose
cells, called âghost cellsâ.

Ulcerated necrotic stage: there is loss of epidermis and reepitalization
attempt in the borders of the ulcer. The adjacent epidermis is often hyperplastic
(pseudoepitheliomatous hyperplasia). The base of the ulcer exposes the dermis
with necrotic material and fibrosis. Necrosis of the subcutaneous tissue and
dermal collagen, with formation of âghostâ cells, is accompanied by edema,
minimal inflammation, and presence of numerous, predominantly extracellular
BAAR in clusters. Necrosis by coagulation affects the subcutaneous cellular
tissue and fascia similarly to the non-ulcerative phase. Vasculitis and extensive
areas of calcification in the lower portion of the dermis are frequently observed
(Figures 4A, B,
C and D).

Initial healing stage (of organization and granulomatous): it is
characterized by the start of a granulomatous response in the dermis and subcutaneous
cellular tissue. Epithelioid cells, Langhans giant cells and lymphocytes are
present in this phase. Eventually, these cells rearrange to form tuberculoid
granulomas. Foamy macrophages, lymphocytes,
and plasmatic cells are sometimes seen in the margins of necrotic tissue.
The appearance of granulous tissue indicates the beginning of the ulcer healing
process. In this stage, BAAR are rarely found in the histopathological examination.39

Late healing stage: fibrosis and atrophic epidermis.

Histopathological findings are considered unspecific;
however, considering the different findings altogether, it is estimated that the
sensitivity of the anatomopathological exam is around 90%. The sensitivity of the
Ziehl-Neelsen staining procedure is between 40 to 80%.42 In conclusion,
the most characteristic findings of a histopathological study of BU lesions are necrosis
of the subcutaneous tissue and of the dermal collagen accompanied by minimal inflammation
(despite the extensive necrosis observed), and predominantly extracellular acid-alcohol
resistant bacilli (BAAR). Neutrophils can be found in the necrotic material. This
mild inflammation could be explained by the action of exotoxin, which causes necrosis
of adipose cells and of the inflammatory infiltrate. 44

CLINICAL PROFILE

Non-tuberculoid mycobacteria are present in the
environment and are in permanent contact with humans and animals. Therefore,
the colonization of clinically healthy individuals by these bacteria is very
common.14 Contact with M. ulcerans may result in the colonization
of healthy tissue without infection. Evolution to the clinical manifestation
of the disease depends primarily upon the host's defenses. Another hypothesis
is the self-resolution of the primary infection, being thus never noticed. The
disease may cause subclinical symptoms or even develop an asymptomatic profile,
remaining latent, as shown in Figure 5. Later, the patient
may have the latent focus activated and manifest the clinical symptoms and signs
of the disease. Sometimes, only a superficial trauma is necessary for the reactivation
of the infection focus, with a shorter incubation period (about 15 days) than
the typical one, between 2 and 3 months.14 Australian authors have
reported the case of a patient, most likely carrying the latent disease, who
after immunosuppressive therapy with corticosteroids developed disseminated
BU.45

The disease caused by M. ulcerans has a spectrum
of clinical forms mostly associated with the time between the onset of the disease
and when the patient seeks a health center for diagnosis. The average incubation
period is from two to three months.14 After primary infection, the disease
can remain localized or disseminate. Many factors contribute to the evolution of
the disease, such as the immunological status of the host, the size and depth of
the inoculation site, and the virulence of the strain.14,22 The preulcerative
form of the disease often does not make the patient seek medical assistance and this
period may vary from a few weeks to months.

Clinically, BU can be divided into pre-ulcerative
stage (papule, nodule, plaque, and diffuse edema) and ulcerative stage, which may
be represented by small ulcers (smaller than 5 cm) and large ulcers (larger than
5 cm). It can also be classified into localized disease (papule, nodule, and ulcer)
and disseminated disease (plaques, diffuse edema, and metastasis).14,43

The initial stage of Buruli ulcer often starts
with a painless and mobile skin nodule, with less than 5 cm of diameter, that
ulcerates usually after a few weeks. It forms an ulcer with poorly demarcated
borders, making it appear smaller than it really is (Figure
6A). In the Australian population,16 it is more common for patients
to notice a small pustule or papule, often attributed to insect bites, without
the nodular phase. This papule often has less than 1 cm of diameter and is accompanied
by erythema in the adjacent skin. This form of the disease has not been reported
in Africa.14 The ulcer develops due to perforation of the necrosis
above the epidermis There is no pain or, if present, it is reported as very
mild. Borders are characteristically poorly demarcated, undermined, and there
is edema in the adjacent skin. The ulcer may remain small, with 1 to 2 cm of
diameter, and it is more susceptible to self-resolution (Figure
6B). However, ulcers frequently become larger and destroy the skin around
them. They may affect bone tissue and develop into disseminated disease (Figure
6C). Their borders are hyperpigmented and their background, necrotic. The
disease can also present with a large area of marked induration, diffuse edema
in the legs and arms or a well-demarcated plaque (Figure 7A).7
Plaques are raised, hard, painless and with a certain degree of depigmentation
or spotted erythema. They can have more than 2 cm of diameter, possibly reaching
15 cm. They can develop into large ulcers with irregular borders. When there
is only one edema, the profile is more diffuse, without a Godet sign, and with
poorly demarcated borders. Edematous lesions can affect an entire limb and a
large portion of the trunk. After a few days or weeks exulcerations are formed
in these areas.7

Lesions can develop in new areas, distant from
the original lesion, which characterizes a metastatic form of the disease. This
evolution of the clinical condition can be explained by the lymphatic or blood
system, especially in relation to the disseminated form of the disease.14

Strains of M. ulcerans isolated from different
clinical forms of the disease in a particular geographical region appear identical,
suggesting that host factors may play an important role in the establishment
of the various clinical presentations.7,16 Due to the local immunossupressive
properties of mycolactone or, perhaps as a consequence of other unknown mechanisms,
the disease evolves without pain, fever or systemic inflammatory response.15
This may partly explain why affected individuals do not seek immediate treatment.
Nevertheless, without treatment, large ulcers develop. The base of the initial
ulcer often contains a whitish, frothy-like secretion; sometimes it can form
crusts. The skin surrounding the lesion becomes increasingly pigmented.7
When ulcers are large, they may affect an entire extremety or a large portion
of the trunk (Figure 7B).

One of the consequences of an extensive ulcer is
the fact that it may affect bone tissue, increasing the risk of osteomyelitis,16,46
and later lead to deformities and even amputations. Involvement of other organs is
extremely rare.22 Metastatic osteomyelitis has also been reported and
it can affect approximately 10% of the patients with BU. It is directly proportional
to the number of skin lesions.16

Involution of lesions may result in atrophic
sequelae or symmetrical scars, sometimes hypotrophic or keloid-like, with contractures
and impairment of the function of limbs when localized near or over joints.
Scars may restrict limb movement, limiting the patient's ability to perform
daily activities and making participation in work activities difficult (Figure
8).47,48 The cosmetic aspect of a scar may also cause social
problems, withdrawing the patient from routine activities. Permanent disabilities
affect around one fourth of the patients. 7 The disease may affect
any part of the body, but in about 90% of the cases lesions develop in the limbs,
with nearly 60% of all lesions occuring in lower limbs.7,8

Differently from tuberculosis (TB), there is
no evidence that HIV infection predisposes individuals to Buruli ulcer.12
But the disseminated form of the disease associated with HIV has been previously
reported. 49,50 There is little seasonal variation in the incidence
of the disease,8 but studies have shown that in Australia, Papua
New Guinea, Cameroon, Uganda, Ghana, and Côte D'Ivoire there is a slight
higher incidence of BU in relatively dry periods.51

Factors associated with poor nutrition, such as
hypoproteinemia or anemia, have been associated with the development of symptoms
and the susceptibility of the host to BU.16,51 This could be explained
by a defficiency in micronutrients such as zinc, which lowers the defenses against
bacterial toxins and reduces the function of T cells and immunity mediated by cells.
In addition, lack of knowledge about the disease, poor hygiene, infrastructure problems
such as poor living conditions or lack of sewage and medical resources, little access
to health services, risky cultural practices, poor nutrition, and general poverty
increase the risk of contact with and infection by aggressive pathogens.51

DIFFERENTIAL DIAGNOSES

Differential diagnosis depends upon the stage of
presentation of the disease and relevant conditions in the area where the patient
lives.8 In a few endemic countries, particularly in West Africa, Buruli
ulcer may be confused with onchocercoma (onchocercosis nodules), noma (cancro
oris), bouba, nodular form of leishmaniasis, spinocellular carcinoma, Kaposi
sarcoma, cutaneous tuberculosis, pyoderma gangrenosum, leprosy, and syphilis.8,14

Plaque and edematous BU can simulate profound mycosis,
erysipelas, bruise, lupus vulgaris, eczema, disseminated sarcoidosis with plaques,
necrobiosis, lipoma, epidermal cyst, lymphadenitis or lymphadenopathy, and hydradenitis.
The differential diagnosis of the edematous form of the disease is osteomyelitis
due to other causes, pyomyositis, elephantiasis, renal or cardiac insufficiency edema,
anemia, malnutrition and tumor lymphatic compression.14

Ulcerative lesions may be confused with tropical
ulcer (lower limbs).8 However, tropical ulcers are often painful and found
only in the lower part of the legs. Leishmaniasis is an important differential diagnosis
in South America, and spinocellular carcinoma can also present as ulcers. The undermined
border of the ulcer orients to the diagnosis of pyoderma gangrenosum. There is still
the possibility of diagnostic confusion with necrotizing fasciitis, sporotricosis,
anthrax, and other tropical phagedenic and stasis ulcers.14

In the healing form, differential diagnosis should
be made with scars resulting from third degree burns and healing lesions of chronic
osteomyelitis.14

Laboratory diagnoses are not commonly used to make
decisions about treatment due to logistic and operational difficulties.16
Even though most health professionals in endemic regions are able to arrive at a
precise clinical diagnosis, microbiological confirmation is important, whenever possible.
14 This measure helps to elucidate the real prevalence and incidence of
BU, confirm new foci of the disease, and verify relapse or reinfection after treatment.
Laboratory diagnosis can also be used to confirm the clinical diagnosis retrospectively
on swabs and tissues removed during treatment, but this is rarely done. Sample collection
depends upon the clinical form of the disease and the objective of the test being
performed.8,14 Two samples are often collected per lesion.43,53
Multiple swabs are taken from the border of lesions, since the center is often negative
for M. ulcerans. In patients undergoing surgery, samples should be collected
from the tissue removed for bacteriological and histopathological analysis.14,43
To confirm osteomyelitis, curettage of the bone tissue should be performed. Despite
improvements in material collection techniques, access to competent laboratories
to read these exams is complicated.

Five laboratory methods to confirm the disease are
often used:

Direct Smear Examination
- An examination done on swabs from ulcers or smears from tissue biopsies that can
be promptly conducted at local health facilities where TB microscopy is also done.
7 The exam is conducted through the acid-fast (Ziehl Neelsen) stain procedure.
Nevertheless, the sensitivity of this method is low (about 40%)18 because
M. ulcerans numbers tend to decrease over time. It is important to emphasize
that the positivity of the test varies with the clinical form of the disease. It
is more useful in the ulcerative stage,8 but if the lesion is not ulcerated,
a skin biopsy is sufficient for the exam. In the nodular form, positivity may reach
60% and in the edematous form, it may reach up to 80%, both in the direct examination
and culture.16 It is considered by many the easiest and most accessible
method to arrive at the diagnosis.

Culture of M.
ulcerans - A procedure done on swabs from ulcers or tissue biopsies through
the Lowenstein-Jensen medium that takes 68 weeks or more; sensitivity is approximately
2060%.7 It is especially difficult to culture M. ulcerans when
the sample is taken from bone tissue.16

Polymerase chain
reaction (PCR) - A test whose results can be obtained within two days on swabs
of ulcers or tissue biopsies; sensitivity is around 98%.2,7 Most studies
use the IS2404 sequence.2,8 The PCR technique has been refined with the
addition of uracil-DNA glycosylase and deoxyuridine triphosphate to the mixture instead
of deoxythymidine triphosphate, which reduces the risk of false positive results
due to contamination.54 PCR with lyophilized reagents and transportation
buffers has also been developed to overcome technical difficulties in the tropics.
54 The positivity of PCR and histopathological tests does not vary with
the clinical form of the disease.

Histopathology - A method that requires tissue biopsies; sensitivity
is about 90% and is useful for differential diagnoses when the results of
other methods are negative. It should be done with a scalpel, thus avoiding
the use of punches. The incision should cover the border of the lesion
and extend into the subcutaneous tissue. It may be up to 90% sensitive;7
in a study conducted in Ghana, despite having found a sensitivity of about
82%, the authors considered this to be the most sensitive method.53

Fine needle aspiration - This technique is used in cases of nodular
lesions and allows the collection of material for later research, such as
direct examination and culture.14

Frequently, some laboratory methods, such as PCR,
are limited to reference and research laboratories, often remote from endemic areas.
Usually, in routine clinical practice cases are managed without microbiological
confirmation. Four laboratory tests are currently available to confirm the diagnosis
of BU: 1  direct examination of secretion with BAAR investigation and Ziehl Neelsen
stain or auramine O; 2  culture; 3- PCR for the IS2404 sequence, and 4- histopathology.
14 The WHO recommends that at least two laboratory tests be carried out
for diagnostic confirmation, making the occurrence of false-positive and false-negative
results more difficult. A simple and fast diagnostic test for BU is needed because
the initial disease (nodule) can be treated locally and inexpensively. The WHO is
reconsidering its early recommendation that two confirming tests were needed to arrive
at a conclusive dignosis.8

TREATMENT

Sometimes localized lesions may spontaneously recede;
however, without treatment, most cases of BU result in physical deformities that
lead to disability, psychological problems, and stigmas. Early detection of active
cases, proper treatment, and complete joint movement of the affected area are essential
for the prevention of disabilities.

According to the WHO, the following are the current
recommendations for treatment:7,8

A combination of rifampicin and an aminoglycoside (streptomycin/amikacin)
for eight weeks as a first-line treatment for all forms of the active disease.
Nodules or uncomplicated cases can be treated without hospitalization. Side
effects have been reported, but are considered rare and are listed in Chart
1. The recommended doses of rifampicin and streptomycin are: rifampicin,
10 mg/kg of body weight, taken orally and daily for eight weeks; streptomycin,
15 mg/kg of body weight, taken intramuscularly and daily for eight weeks (Chart
2). This drug is contraindicated for pregnant women. Amikacin is a viable
alternative if streptomycin cannot be used and it is administered in the dose
of 15mg/kg of body weight, instramuscularly, daily, for eight weeks.52

Surgery to remove
necrotic tissue and skin grafts to aid in healing make recovery faster and more efficient.
Surgery is performed to correct skin defects, contractures and the function of affected
joints, and for cosmetic reasons.

Interventions to
minimize or prevent physical, emotional and social disabilities.47,48
The best prevention is to teach the population and health professionals how to diagnose
and later treat the disease. Other actions, associated with antibiotic therapy, are
needed to avoid complications and disabilities. Education is the best guarantee that
patients and their families will learn about and participate in their selfcare from
the moment of the diagnosis. The most important measures are:

Dressings that aid in healing, preventing the
contracture of soft tissues and joints;

Exercises and positioning of the affected part
to avoid contractures;

Control of the edema;

Care with the skin and scar, keeping them hydrated,
lubricated, mobile (without adhesions), and protected;

Participation in daily activities;

Good nutrition and diet that aid in healing;

Good hygiene, which helps to avoid infections;

Awareness that when needed, help should be
asked of others.

For a long time, the treatment of BU was exclusively
surgical and often mutilating. Treatment with drugs was only implemented in 2005
with the association of rifampicin and streptomycin so that the lesions and edema
could be reduced, helping surgical excision.55 The surgical treatment
of BU initially consisted in the radical excision of all necrotic tissue and a portion
of normal tissue, followed by skin graft. Studies have shown that antimicrobial drugs
(rifampicin, aminoglycosides, macrolides, and quinolones) inhibit the growth of M.
ulcerans in vitro and in vivo and that treatment combinations containing
aminoglycosides were more efficient than those without this drug.8 A previous
study conducted by the British Research Council in Uganda showed the beneficial effect
of clofazimine.8 In another study in Ghana, patients with a clinical diagnosis
of the nodular form of the disease were randomized to receive rifampicin, 10 mg/kg,
and streptomycin, 15 mg/kg for two, four, eight or twelve weeks. After these weeks,
all patients underwent surgery and skin biopsies were analysed by PCR, culture, and
histopathology. In patients treated for two weeks, viable M. ulcerans could
still be cultured, whereas in all the patients who were treated for at least four
weeks, living bacilli could not be isolated. Clinically, however, most patients responded
well to streptomycin and rifampicin; in some cases, lesions receded completely.55

Nienhuis et al. conducted a study comparing the
use of streptomycin and rifampicin for eight weeks with the regimen of rifampicin
for eight weeks and streptomycin for four weeks, associated with the use of oral
clarithromycin for four more weeks. The authors showed that 96% of the patients who
used streptomycin for eight weeks and 91% of those who used streptomycin for four
weeks followed by oral clarithromycin for four weeks had their lesions healed and
were cured after a year without relapse after antibiotic treatment. The difference
between the two therapeutic regimens was very small, suggesting that they are both
efficient. This study also demonstrated that initial and limited lesions of BU can
be effectively treated without surgical procedures.56,57 Previously, studies
showed that initial lesions removed with a simple excision had a relapse rate of
16% after a year. Even after evidence about the therapeutic effect of antibiotics
in the treatment of BU,56,57 surgery is still necessary in some cases.
The type of surgical treatment will depend on the clinical form of the disease.
Papules, nodules, and small ulcers are excised with simple closure. The avoidance
of aggressive surgical procedures produces more satisfactory functional results.58
It has been observed that extensive and unnecessary surgeries can damage healthy
tissues and do not prevent relapses. For patients with facial lesions, surgery is
not a treatment option. Patients should be referred to an orthopedist when there
is bone tissue involvement.

The WHO has created a didactic division52
into treatment categories according to the size of the lesion and other complications
(Chart 3). The three treatment categories seek to help manage
the disease and do not cover all of its clinical forms. A careful and adaptive
analysis of the clinical condition should be conducted to control all forms
of the disease. Moreover, findings from Nienhuis et al. should be considered
so that unnecessary surgical procedures can be avoided.

Complete mobility of the affected area when diagnosis
is accomplished, during, and after treatment may prevent contractures due to the
healing process. Patients and their families should learn how to make these movements
as part of their daily self-care routine. The health team and the community health
agent must instruct patients and their families and practice the movements with them.
Most physiotherapy and rehabilitation services are offered in reference centers
for the treatment of BU in endemic countries. Unfortunately, access to these centers
is limited, but they are very important to complement surgical treatment. 7,47
Other topical treatments have been suggested, including thermal treatment, hyperbaric
oxygen therapy, medicinal argyle, powder phenytoin, and nitrite ointment.8

Recurring infections are a problem, especially in
immunocompromised individuals and patients with disseminated disease. They also occur
frequently in patients who develop osteomyolitis caused by M. ulcerans. Since
patients with lesions that affect the joints are prone to developing contractures,
most of these patients benefit from actions to prevent disabilities that include
activities or exercises to maintain or improve movements, from the time of diagnosis
until after treatment. If joint movement does not improve or worsens, the patient
should be referred to reference centers where he can undergo physiotherapy.2
Recurrence rates after treatment with antibiotics are lower than 2%, compared with
the 16-30% rate of exclusive surgical treatment.7,56 These data motivated
a change in the treatment strategy for BU, which was geared towards surgical treatment
until 2004.

MONITORING AND PROGNOSIS

After conclusion of the antibiotic treatment,
the patient should be monitored for at least 10 months so that cure can be confirmed.
Monitoring is also important for the diagnosis of possible complications and
to notice any recurrences.52 Execution of the ten tasks listed in
Chart 4 can prevent or
minimize disabilities and should be initiated at diagnosis and continue after
the treatment is concluded, when necessary.59

The evolution of the disease may vary in severity.
In some areas, ulcers heal slowly with fibrosis and retraction. In the limbs, retraction
can be extensive and impair their function permanently. Facial lesions can lead to
serious cosmetic deformity or even loss of the eyeball. Death due to infection by
M. ulcerans is rare, although secondary bacterial infection may aggravate
extensive areas of ulceration. 16 Often, the general condition of the
patient is not affected.12 Spinocellular carcinomas have been reported
to develop in healing areas after BU.60 Care59,61 with scars
is very important to reduce skin dryness, fissures, trauma during work or leisure,
sunburns, and problems with the mobility of soft tissue and joints.47

PREVENTION

Prevention of BU is difficult because there is no
clear knowledge about the forms of transmission of the disease or isolation of a
specific antigen to develop a vaccine. The Calmette-Guerin bacillus (BCG) appears
to offer some short-term protection against the disease. Even though there is still
some debate, BCG vaccine seems to protect against osteomyelitis. 2,7,62

Due to the absence of efficient tools to control
BU, current control strategies aim at reducing the prolongued suffering, disability,
and socioeconomic burden associated with the disease.7,8 In the annual
meeting of the WHO for the control and management of BU, held in Geneva, Switzerland,
in March of 2005, the following control strategies were suggested:8

Early detection of
cases in communities through information, education, and communication;

Standardized storage
of data and communication system using forms BU 01 and BU 02 and a HealthMapper;

Strengthening of
reference health services;

Monitoring and evaluation
of control activities.

CONCLUSION

Buruli ulcer, caused by Mycobacterium ulcerans,
1 has been reported in more than 30 countries, especially with tropical
and subtropical climate,7 but its epidemiology remains unclear, even in
endemic countries. For instance, it is recognized as a public health problem in Uganda,
Nigeria, Gabon, Ghana, Togo, French Guiana, Cameroon, Liberia, Côte D'Ivoire, Malasia,
Papua New Guinea, and Benin.7 The limited knowledge about the disease,
its focal distribution, and the fact that it affects mainly rural poor communities
contribute to the low reporting of cases.

Similarities between the climate, vegetation and
habits in Brazil and endemic countries suggest that Brazil may be a likely focus
of the disease. Lack of knowledge about the disease by health porfessionals makes
the identification and epidemiological monitoring of the disease difficult in Brazil.
In 2007, the first case of BU in Brazil was published13 and, in November
of 2009,20 McGann et al. reporte the occurrence of a second case in the
Brazilian territory. This shows that the presence of the disease in national territory
is plausible.

Despite the great knowledge about the clinical profile
of BU in endemic countries, in other areas this diagnosis may be overlooked. Therefore,
physicians should be educated about BU, because early diagnosis and proper treatment
aid in the prevention of functional disabilities resulting from this infection.

ACKNOWLEDGEMENTS

The authors would like to thank the initiative
of Dr. Kingsley Bampoe Asiedu, physician responsible for the Global Buruli Ulcer
Iniciative/GBUI of the World Health Organization (WHO). Dr. Asiedu alerted us
to the importance of this topic and recommended that an extensive continuing
medical education article be written to train Brazilian dermatologists and physicians
in other specialties to diagnose BU in Brazil. He is also responsible for granting
permission to use images from the homepage of the WHO (www.who.int/buruli/photos/en/index.html).

59. Lehman L, Saunderson P. Ten Tasks to Prevent Disability in Buruli Ulcer, Tasks for people affected by Buruli Ulcer who want to prevent disability - "I Can Do It!" American Leprosy Missions, 2009. (currently used in community based POD training and is being made into a flip chart which is expected to be adopted by WHO. Examples will be shown at the 2010 Geneva BU meeting) [ Links ]

2) What is the likely cause of change in the
epidemiology of Buruli ulcer?

a) It has been attributed to flooding, population
growth, mining, wood extraction from tropical forests, and river damming.
b) Migration from and to rural and urban areas, leading to the development of
new cases in large urban centers.
c) Change in economic activities leading to the economic growth of most countries
previously considered endemic.
d) Higher notification of cases in countries previously not considered endemic

3) How many cases of the disease have been reported
in Brazil?

a) none
b) one
c) two
d) twenty-two

4) Regarding the form of transmission of the
disease, it is incorrect to state the following:

a) An environmental factor associated with slowflowing
water, to which populations who live by the water are exposed, might play a
role.
b) There are reports of a possible transmission through insect bites or insects,
probably acquatic insects of the order Hemiptera (Naucoridae and Belostomatidae).
Studies have shown that the Naucoris mosquito is naturally colonized by M. ulcerans
in endemic areas.
c) There are no reports of patient-to-patient transmission.
d) The agent of BU can enter the human body through several types of trauma,
from mild ones, such as a hypodermic injection, to severe, such as landmine
injuries.

5) It is correct to state the following about
the etiologic agent of BU:

a) This mycobacterium is a predominantly intracellular
BAAR and can live freely in the environment, especially in acquatic environments.
b) It is slow growing and needs a specific culture medium, different from the
one used for other mycobacteria.
c) There is some variation between the strains of M. ulcerans found in different
georaphical areas (Africa, America, Asia, and Australia) that can be observed
with the use of the PCR technique.
d) There appears not to be a direct relationship between virulence and the number
of IS2404 copies.

6) Mycolactone is a heat-stable exotoxin, lypophilic,
that belongs to the group of macrolides and causes extensive, chronic and necrotizing
damage to the papillary dermis, subcutaneous fat, and muscles, resulting in
deformity and disability. It is incorrect to state the following about this
molecule:

a) The molecule is active in extremely low concentrations
and is not present in laboratory cultures.
b) Mycolactone molecules, when injected in laboratory animals, are capable of
producing massive necrosis similar to that observed in animals innoculated with
M. ulcerans.
c) Mycobacterium marinum and M. ulcerans are philogenetically close and may
share from 98 to 99.8% of their genetic material, but the production of mycolactone
by M. ulcerans differentiates the two species.
d) M. liflandii also has the IS2404 sequence and all the genes that codify mycolactone.
This is why it is impossible to distinguish it from M. ulcerans.

7) The following is not characteristic of the
histopathological evolutionary stages of BU:

a) Late healing stage - fibrosis and atrophic
epidermis.
b) Initial healing stage - without granulomatous response. Numerous BAAR are
still found.
c) Non-ulcerated necrotic stage - the epidermis is intact, but it is often hyperplastic.
The upper dermis is preserved, with varying degrees of colagen degeneration
and discreet infiltration of inflammatory cells with the presence of denucleated
adipose cells, called "ghost cells".
d) Ulcerated necrotic stage: there is loss of the epidermis and attempt of reepitelization
in the borders of the ulcer. The epidermis is hyperplastic, there is minimal
inflammation, and presence of numerous BAAR.

8) What is the main factor that determines which
type of clinical lesion we will find in a patient?

a) Strain of the mycobacterium causing the disease
b) Work activity of the patient
c) Patient's immunity
d) Evolution time

9) What is the incubation period of the disease?

a) 3 months
b) 7 days
c) 1 year
d) 3 weeks

10) Buruli ulcer can present with a large area
of marked induration, diffuse edema in the arms and legs or a well-demarcated
plaque. It is correct to state the following about this clinical phase of the
disease:

a) It is also called disseminated BU.
b) Plaques are raised, indurated, painless, hyperpigmented and smaller than
2 cm.
c) It does not progress to an ulcer.
d) It never affects the entire limb, only part of it.

11) It is incorrect to state the following about
the clinical profile of BU:

a) Strains of M. ulcerans isolated from various
clinical forms of BU in a particular geographical region appear identical, suggesting
that host factors may play an important role in the determination of the clinical
presentations of the disease.
b) The base of the initial ulcer usually contains a whitish, foamy secretion
and sometimes it can form crusts.
c) One of the consequences of an extensive ulcer is the involvement of bone
tissue, with high risk of osteomyolitis and later deformities or even amputations.
d) Due to the local immunological properties of mycolactone, the disease progresses
with intense pain, high fever, and systemic symptoms.

12) It is correct to state the following about
the healing phase of the disease:

a) The cosmetic aspect of the scar seldom causes
social problems or withdrawal from daily activities.
b) Permanent disabilities affect about half of the patients.
c) The risk of disability increases with the development of osteomyelitis during
the course of the disease.
d) The involution of lesions may result in atrophic sequelae or scars with contractures
and impairment of the function of limbs when lesions occur on extensor areas.

13) Many diseases can be possible differential
diagnoses of Buruli ulcer. It is correct to state the following:

a) In West Africa, BU can be mistaken for onchocercoma
and nodular leishmaniasis.
b) The presentation of the disease with plaques and edema is completely different
from any profound mycosis. Differential diagnosis with this class of diseases
is done when the patient is in the ulcerative phase of BU.
c) Tropical ulcer is rarely confused with BU because it more commonly affects
the upper limbs; however, this diagnosis should always be contemplated.
d) Leishmaniasis is an important differential diagnosis, but not in South America,
where it is a rare occurrence.

14) All the following are clinical criteria for
suspicion of BU, except:

15) Laboratory diagnoses are not commonly used
to make decisions about treatment due to operational and logistic difficulties.
It is incorrect to state the following about the possile techniques employed:

a) Laboratory diagnosis can also be used to confirm
clinical diagnosis retrospectively on swabs and tissues removed during treatment.
b) Bone tissue curetage should be performed to confirm osteomyelitis.
c) Histopathology is useful for differential diagnosis when the results of other
methods are negative. It is up to 90% sensitive.
d) Culture of M. ulcerans takes from 6 to 8 weeks and is approximately 100%
sensitive.

16) Which of the following corresponds to recommendations
of the WHO for the proper treatment of BU?

a) Surgery should not be performed to remove
necrotic tissue if wound healing causes joint impairment and cosmetic burden
for the patient.
b) Due to the high rate of complications per and post-surgery, surgery is not
performed to correct defects, contractures, and the function of the affected
joints. Physiotherapy is used for these purposes.
c) Association of rifampicin and streptomycin for eight weeks as a first-line
treatment for all forms of the active disease.
d) The recommended doses of rifampicin and streptomycin are: rifampicin, 15mg/kg
of body weight, taken orally, daily, for eight weeks; streptomycin, 10 mg/kg,
taken intramuscularly, daily, for eight weeks. This drug is contraindicated
for pregnant women.

17) It is incorrect to state the following about
alternative treatments of BU:

a) Many antimicrobial drugs (rifampicin, aminoglycosides,
macrolides, and quilones) appear to be effective based on clinical impressions.b) Studies (6) have shown that macrolides,
quilonones, and aminoglicosides inhibit the in vivo growth of M. ulcerans.
c) Treatment combinations with aminoglycosides are more efficient than those
without this drug.
d) There is a beneficial effect of clofazimine on M. ulcerans.

18) It is correct to state the following about
the prevention of disabilities:

a) After the implementation of the so-called
"10 tasks", the benefit of physiotherapy started being questioned.
b) Movement of the affected limb from the time of diagnosis is essential for
the prevention of disabilities.
c) The "10 tasks" recommended by the WHO should only be executed by competent
professionals in reference centers.
d) The main cause of disabilities is the level of immunological response against
the infection and is not related with a delay in treatment.

19) After treatment is completed, the patient
should be monitored:

a) For at least 6 months
b) Only if there are functional complications
c) Every two years, after the first year
d) Monthly, for at least 10 months

20) Prevention of BU is complicated because there
is no clear knowledge about the forms of transmission of the disease or isolation
of a specific antigen for the development of a vaccine. In spite of this, it
is incorrect to state the following about attempts to prevent the disease:

a) Patients who received the BCG vaccine are
less likely to develop osteomyelitis.
b) The bacillus Calmette-Guerin (BCG), when administered in two doses, appears
to offer protection against the disease.
c) In the absence of adequate tools to control BU, current control strategies
aim at reducing the prolongued suffering, disability, and socioeconomic burdens
associated with the disease.
d) Early detection of cases in communities and implementation of disability
control were established by the WHO in 2005.